The present disclosure relates to a tread of a tire for a motor vehicle comprising a block of rubbery material, the length of which is very much greater than its width, and more particularly the invention relates to a tread comprising a block having a plurality of sipes.
Document FR759592 discloses the use of sipes in a tire tread for increasing the grip of this tire. Specifically, the use of sipes makes it possible to increase the number of edge corners on the tread surface of the tread thereby notably encouraging grip on wet ground. A sipe means a cut in the tread delimiting walls of material, the width of this cut being suitable for allowing these walls of material to come at least partially into contact as they enter the contact patch in which the tire is in contact with the ground. The width of a sipe is thus at most equal to 2 millimeters (mm).
Document FR43383 which is in addition to document FR759592 discloses the use of oblique sipes. The oblique sipes delimit sub-blocks of rubbery material. Now, the resistance of these sub-blocks to wear varies according to the width of these sub-blocks, that is to say according to the distance between two adjacent oblique sipes. Furthermore, the use of oblique sipes in the tread may lead to additional running noise.
There is therefore a need to offer a tread which, over all or part of this tread, has a plurality of oblique sipes that are distributed in such a way as to optimize the resistance of this tread to wear while at the same time limiting the risks of generating running noise.
A “tire” means all types of resilient tread whether or not it is subjected to an internal pressure.
The “tread” of a tire means a quantity of rubbery material delimited by lateral surfaces and by two main surfaces, one of which is intended to come into contact with a roadway when the tire is running.
A tread “block” means a raised element delimited by grooves and comprising lateral walls and a contact face, the latter being intended to come into contact with the ground during running.
A “groove” means a cut in the tread delimiting walls of material, the width of this cut being such that the walls associated with this cut cannot come into contact with one another under normal running conditions. The width of a groove is greater than 2 millimeters.
A “sipe” means a cut in the tread delimiting walls of material, the width of this cut being suited to allowing the walls of the sipe to come at least partially into contact as they pass through the contact patch in which the tire is in contact with the ground. The width of a sipe is less than or equal to 2 millimeters.
An “axial direction” means a direction parallel to the axis of rotation of the tire.
A “circumferential direction” means a direction tangential to any circle centred on the axis of rotation. This direction is perpendicular to the axial direction.
An “oblique direction” means a direction that has an axial component and a circumferential component neither of which is zero.